1. Field of the Invention
The invention relates generally to a method for forming a multi-compartment bag, in particular a two-compartment bag, and more specifically a method for forming a two-compartment bag on a vertical form-fill-seal (VFFS) machine.
2. Description of the Related Art
Prior art processes for forming multi-compartment bags tend to be complex and generally offer limited flexibility for modifying the volume of the second compartment relative to the volume of the first compartment.
DE 10 2007 025 786 A1 discloses a method for forming tubular bags. Two consecutive bags are left attached to each other. The two bags necessarily have the same diameter. The volume of the second bag can be varied by varying the location of a transverse seal.
DE 20 2004 002 244 U1 discloses a “chain bag” comprising at least two compartments that are separated from each other by a heat seal. The construction does not permit the two compartments to be filled simultaneously. The two compartments have identical cross sections.
EP 2 567 898 A1 discloses a detergent package made of a water soluble material. The package has an inner compartment fully encircled by an outer compartment.
U.S. Pat. No. 5,758,473 discloses a method for manufacturing packages for liquid food products in which a flexible sheet material member is folded into a tubular shape so that longitudinal strips extend outwardly. Suitable welding lines are made so as to form a channel compartment that is closed at one end and in communication with an inside of the package.
US 2012/0125947 discloses a flexible bag comprising a dispensing portion, a panel forming a first compartment, a second compartment extending from the first compartment, and an elongated grip disposed at least in part in the second compartment.
US 2003/0009989 discloses multiple side-by-side packages produced on a vertical form, fill, and seal machine by using a former/delivery tube assembly designed for this purpose.
U.S. Pat. No. 6,622,459 B1 discloses a process for continuously manufacturing and filling multiple cavity bags. According to the method a sheet of plastic material is fed along a forming column; and the plastic material is sealed along a first longitudinal seal to form a sleeve. The sleeve is fed along two cores and sealed in central and bottom parts.
Thus, there is a need for a multi-compartment bag in which all compartments can be filled simultaneously. There is a further need for such bag in which the volume of the one compartment can be varied independent from the volume of the other compartment or compartments. There is a further need for such bag having a first compartment folded against a second compartment during transportation and shelf display. There is a further need of such bag suitable for heating a food material contained therein in a microwave oven.